The gastrin releasing peptide, GRP, is differentially expressed in brain metastatic breast cancer.
Metastasis to the brain is a clinical problem in patients with breast cancer (1-3). We mined published microarray data (4, 5) to compare primary and metastatic tumor transcriptomes to discover genes associated with brain metastasis in patients with metastatic breast cancer. We found that the gastrin releasing peptide, encoded by GRP, was among the genes whose expression was most different in the brain metastases of patients with metastatic breast cancer as compared to primary tumors of the breast. Molecular functions of gastrin releasing peptide may be relevant to the processes by which tumor cells of the breast metastasize to the breast. Down-regulation of GRP may be an important event for metastasis of primary tumor-derived cancer cells to the brain in humans with metastatic breast cancer.